MONOGAMY, POLYGYNY, AND POLYANDRY: EXPLORING THE GENETIC CONSEQUENCES OF CALLITRICHINE SOCIAL SYSTEMS USING AGENT-BASED SIMULATION

The social system of wild callitrichines is unlike that of any other group of primates. First, individuals of both sexes often reside and mate with one (and sometimes more than one) member of the opposite sex. When more than one same-sexed adult is present, mating and reproduction may or may not be heavily skewed towards a single individual. Second, maturing animals of both sexes often disperse, sometimes with same-sexed conspecifics, but also occasionally take over breeding positions from resident adults. Third, females regularly produce twin offspring, and nonparents assist in rearing these infants. Because genetic studies of wild callitrichines are rare, the consequences of these unique traits for population genetic structure are poorly understood. We use GENESYS, a flexible agent-based population genetics simulation toolkit, to explore the effects of these mating system and dispersal traits on callitrichine genetic structure. We simulate population dynamics in a landscape comprising 36 groups of “tamarins” showing variable degrees of reproductive skew (from complete monopolization of parentage by a single individual of each sex to egalitarian reproduction for all resident adults) and following different dispersal models. Our simulations indicate that mating and dispersal patterns have a marked effect on several population genetic parameters, including the relatedness among animals within groups (and thus on possible inclusive fitness benefits to cooperative breeding) and the relationship between genetic and geographic distance among groups.